XML 18 R45.htm IDEA: XBRL DOCUMENT v3.19.3
Government Contracts - Additional Information (Detail)
1 Months Ended 3 Months Ended 9 Months Ended
Jul. 01, 2019
USD ($)
Jan. 31, 2019
Jul. 31, 2018
USD ($)
Option
Feb. 28, 2018
USD ($)
Apr. 30, 2017
USD ($)
Feb. 28, 2017
USD ($)
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Option
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Sep. 30, 2019
USD ($)
Option
Sep. 30, 2018
USD ($)
May 31, 2019
USD ($)
Mar. 12, 2018
USD ($)
Government Contracts [Line Items]                              
Grant revenue                 $ 4,643,000 $ 658,000   $ 14,517,000 $ 2,274,000    
SPR206 [Member] | DoD, CDMRP and JWMRP [Member]                              
Government Contracts [Line Items]                              
Award received for clinical development $ 5,900,000                            
Non-dilutive funding period 4 years                            
BARDA [Member]                              
Government Contracts [Line Items]                              
Potential contract amount awarded     $ 44,200,000                        
Option exercise | Option     2                        
BARDA [Member] | Base Period Contracts [Member]                              
Government Contracts [Line Items]                              
Potential amount initial funding awarded     $ 15,700,000                     $ 18,100,000  
Potential amount additional funding awarded                           2,500,000  
Overall potential award increased                           $ 46,700,000  
Contract term     3 years                        
BARDA [Member] | Grant [Member]                              
Government Contracts [Line Items]                              
Grant revenue                 4,200,000     9,400,000      
BARDA [Member] | First Option [Member]                              
Government Contracts [Line Items]                              
Potential grant amount awarded     $ 13,600,000                        
BARDA [Member] | Second Option [member]                              
Government Contracts [Line Items]                              
Potential grant amount awarded     $ 14,900,000                        
U.S. Department of Defense [Member]                              
Government Contracts [Line Items]                              
Contract term             2 years                
Potential grant amount awarded             $ 1,500,000                
U.S. Department of Defense [Member] | Grant [Member]                              
Government Contracts [Line Items]                              
Grant revenue                 200,000     200,000 200,000    
U.S. Department of Defense [Member] | Grant [Member] | Maximum [Member]                              
Government Contracts [Line Items]                              
Grant revenue                   100,000          
Niaid [Member]                              
Government Contracts [Line Items]                              
Contract term           12 months                  
Niaid [Member] | Spero Cantab [Member] | Cantab Anti Infectives Ltd. [Member] | Cantab Agreements [Member]                              
Government Contracts [Line Items]                              
Grant revenue                   400,000   800,000 1,100,000    
Maximum potential funding from government contract               $ 6,500,000              
Number of option period for funding from government contract | Option               3              
Maximum received fund                       1,300,000      
Amount paid upfront as part of agreement                       300,000      
Niaid [Member] | Spero Cantab [Member] | Pro Bono Bio PLC [Member] | Cantab Agreements [Member] | Research and Development Expenses [Member]                              
Government Contracts [Line Items]                              
Expense associated with amounts payable under agreement                   100,000   200,000 400,000    
Niaid [Member] | Maximum [Member] | Spero Cantab [Member] | Cantab Anti Infectives Ltd. [Member] | Cantab Agreements [Member]                              
Government Contracts [Line Items]                              
Grant revenue                 100,000            
Niaid [Member] | Maximum [Member] | Spero Cantab [Member] | Pro Bono Bio PLC [Member] | Cantab Agreements [Member] | Research and Development Expenses [Member]                              
Government Contracts [Line Items]                              
Expense associated with amounts payable under agreement                 100,000            
Niaid [Member] | Base Period Contracts [Member]                              
Government Contracts [Line Items]                              
Potential grant amount awarded           $ 600,000                  
Niaid [Member] | Grant [Member]                              
Government Contracts [Line Items]                              
Grant revenue                         300,000    
Niaid [Member] | Grant [Member] | Maximum [Member]                              
Government Contracts [Line Items]                              
Grant revenue                 $ 100,000 $ 100,000   $ 100,000      
Niaid [Member] | Option Period Contracts [Member]                              
Government Contracts [Line Items]                              
Contract term       12 months                      
Potential grant amount awarded           $ 400,000                  
Potential grant amount exercised       $ 400,000                      
Contract term extended   12 months                          
Niaid [Member] | First Option [Member] | Spero Cantab [Member] | Cantab Anti Infectives Ltd. [Member] | Cantab Agreements [Member]                              
Government Contracts [Line Items]                              
Number of option period for funding from government contract | Option                       2      
Committed amount from government contract                       $ 5,900,000      
CARB-X [Member]                              
Government Contracts [Line Items]                              
Contract term         12 months                    
Potential grant amount awarded         $ 1,500,000                    
Potential grant amount exercised         $ 0                    
CARB-X [Member] | First Option [Member]                              
Government Contracts [Line Items]                              
Potential grant amount awarded                             $ 400,000
CARB-X [Member] | Grant [Member]                              
Government Contracts [Line Items]                              
Grant revenue                     $ 0   $ 500,000